Papermaker&#39;s felt



April 23, 1963 R. F. BARTZ ETAL PAPERMAKERS FELT 2 Sheets-Sheet 1 Filed Sept. 15, 1961 DIRECTION OF BELT TRAVEL IN RELATION TO WEAVES INVENTORS RAYMOND F. BARTZ HOWARD M. HELLAND -CLIFTON J. VINCENT v BY.

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April 23, 1963 R. F. BARTZ ETAL PAPERMAKERSFELT 2 Sheets-Sheet 2 Filed Sept. 15, 1961 q How/U20 M. HELLAND s 7 Y 3 E N 2 MW m m T Z A NT Y Z B Unite This invention relates to industrial felts of the type referred to as papermaker felts, for use as wet felts in connection with the papermaking industry; or as industrial felts in connection with the manufacture of asbestos shingle or similar articles.

This application is a continuation-in-part of our copending patent application Serial No. 4 8,861 filed August 1, 1960 and now abandoned.

The papermaker expects a felt to support his sheet of paper stock while transporting this sheet toward his dryers, without imparting to it an excessive mark or surface unevenness, and simultaneously to drain water from his sheet at the highest rate possible and to function efiiciently in these respects for the longest possible period of time.

The specifications for felts and the standards of performance expected from felts are different for each position on each paper machine, but there are general minimum physical requirements for felts. 'For example, felts must be sufficiently fine yet porous, and strong and stable as belt structures if the paper-makers expectations outlined above are to be fulfilled.

Historically, felts for papermaking are woven of warp and filling in a multitude of combinations of different weaves, yarn sizes, and yarn constructions (singles, or plys, and hard or soft twist) and yarn fiber content and yarn manufacturing systems. Following the weaving the felts are shrunk to sizes correct for the papermachine positions intended. Within the framework of the papermachine position and the paper product requirement, years of experience have established definite limits on the total weight of the felt required and on the distribution of this weight between warp and filling. Using warp and filling only, any one or all three of these elements (total felt weight, filling weight, and warp weight) can become a limit. Too much of any one of the three can impede passage of water; too little of any one of the three causes dimensional instability and short useful felt life; too little filling weight causes a surface mark; and too little Warp weight causes dimensional instability.

Recently efforts have been made to design felts in which a third component, a batt, is added to the traditional warp and filling by means of a needling process.

States Patent The batt is constructed of multi-layers of webs of fibers not at all oriented; this multi-layered web being driven into and/ or attached to a base fabric by means of barbed needles which pass into and through this batt and then into a woven base fabric composed of warp and filling. The felt need not be shrunk following this procedure, because the needling operation has been substituted for the felting normally obtained during the shrinking or fulling process.

This needling technique has extended some of the limits discussed hereinabove because the third component, the bait, imparts a stability to the felt not before possible when using only two components. The effect may be likened to laminating, as in plywood. However, not all three limits are extended or eliminated because the batt element functions only as filling and as stuffing and thereby as a width-stabilizer. In other words, because the product is of laminated form, it does help stabilize the felt; but because there is no orientation or geometric calculation of the fibers comprising the batt, it does this very inelficiently, and therefore the total felt "ice weight cannot be reduced significantly. Use of the batt makes possible reduction of the warp weight only.

One object of the present invention is to provide a means for extending the limits of all three of the aforementioned elements by employing in felt manufacture a novel principle of construction recognizing that maximum retention of shape and dimensional integrity with minimum weight may be achieved by reinforcing a box or square or rectangle-shaped structure with members which diagonally span the structure in both directions. If the box or square or rectangle has a depth dimension (which is the case here), even greater stability may be achieved by applying such reinforcements to both sides.

In textiles, because the structural members are pliable yarns, cross-tied laminates of two or more fabrics, disposed in biased relation will compose infinite varieties of geometric patterns over the span of the total structure; but in all cases the fabrics diagonally brace each other, thereby achieving optimum stability in combination with minimum weight. Thus, the present invention contemplates a laminate of two or more fabrics disposed in biased relation and integrated to provide a structure wherein the dissipation and transference of tensile and compressive forces is principally a function of the angles of the yarns of the bias-disposed fabric relative to the yarns of the other fabric.

n The integration of the laminate is achieved by use of a needling technique in which bar-bed needles are passed into and through bias-related fabrics as illustrated herewith, one of the fabrics being a core fabric wherein the warp yarns lie in the direction of felt travel, and then if preferred into and through one or more additional alternately biased fabrics. The needles reposition fibers during each stroke according to the paths taken; that is, fibers fro-m the yarns of the fabric first entered by the needles are bent and driven downward into and through the layer (or layers) therebelow, thereby locking the laminate together. The needles are so constructed as to only push the fibers or filaments so that they will not be withdrawn from the positions taken during the downward strokes of the needles, as the needles withdraw. If the barbs of the needles are not filled during their passages through the first (or top) fabric, then fibers from yarns of the second fabric will become attached to the barbs and will be moved downwardly in the manner herein described; and should more than two fabrics be used, fibers from both fabrics will thus become interlocked with the fabrics therebelow.

Still further improved finished felt rigidity and stability may be obtained if the direction of the needle travel is inclined relative to the plane of the laminate, because thefibers will thus be driven angularly through the laminate and will therefore distribute the forces applied to them more efficiently and completely. Alternatively, the needling may be performed to penetrate the fabrics in intersecting directions, whereby the fibers will be interlocked in depth as described hereinabove in the same manner and with the same benefits achieved from yarns 9f the, bias-disposed fabrics in coniunction with the yarns of the core fabric.

Applied to papermakers felts this construction principle makes possible an absolute minimum total felt weight, not obtainable from conventional warp and filling constructions or previous batt-on-base needled constructions. This same statement applies to the element of warp weight; Because both of these can be kept to absolute minimums the third element, (the filling or stuffing or cushion-providing segment) can in the case of the present invention be adjusted substantially independently of any physical requirement of felt stability or felt bal- This means that for the first time in felt construction history it is possible to provide felt construction specifications so as to obtain maximum passage of water and/ or maximum sheet surface smoothness independently of the requirements of strength and stability, and therefore total felt weight.

Another object of the present invention is to provide in the aforesaid type felt constructions enhanced drainage characteristics, by employing in the felt manufacture a novel needling technique whereby back-slanted water channels are formed in the fabric incidental to the needling process.

Numerous additional objects and advantages of the invention will be apparent from the specification hereinafter, and by reference to the accompanying drawing wherein:

FIG. 1 is a schematic illustration of a felt fabrication of the present invention, illustrating an initial assemblage and novel relative orientation of the multiple fabric components of the felt structure of the invention, prior to needling thereof;

FIG. 2 illustrates schematically the operation of needling the fabric components of the invention into the form of a finished felt;

FIG. 3 illustrates schematically the relative orientation of the fabric components of the felt structure in relation to the direction of the felt travel; and

FIG. 4 is a schematic sectional illustration corresponding to FIG. 2 but showing another felt construction of the present invention.

FIG. 5 is a fragmentary schematic illustration of a conventional type papermaking machine employing a wet felt of the present invention;

FIG. 6 illustrates schematically the operation of needling typical fabric components into the form of a finished felt of the present invention;

FIG. 7 is a detail of FIG. 5, on an enlarged scale, illustrating operation of the present invention; and

FIG. 8 is a schematic of an alternative needling operation.

Generally stated, the invention contemplates construction of one form of papermakers felt to comprise a plurality of fabric layers needled together to provide an integral felt; featured by the fact that the core fabric is disposed centrally of the construction and oriented so that the warp yarns thereof run lengthwise of the belt so as to withstand the belt tension loads to the utmost of their capabilities. This core fabric is disposed between balanced bias-disposed fabrics, or below a single balanced bias-disposed fabric, and the assemblage is needled together to provide an integral felt. Thus, the obliquely disposed fabrics mechanically reinforce the core fabric against skewing as the felt traverses the papermaker felt support roller system, and otherwise stabilizes the felt in such manner that a belt may be constructed according to this invention so as to be extremely light-weight and yet will be stable in operation. Thus, it follows that the belt construction will be of improved drainage characteristics whereby the belt will possess an improved production rate.

Referring to the drawing herewith, the felt is illustrated to comprise a centrally located core fabric 10 which may be woven of any suitable form of yarn, with the warp yarns running lengthwise of the belt. At opposite surfaces of the core fabric, are disposed balanced biasoriented woven yarn fabrics 1112, and the asemblage is then needled together by means of any suitable gang needling device such as illustrated at (FIG. 2). As shown in FIG. 2, the needling operation operates to drive fibers vertically from the bottom or roller contacting fabric layer 12 through the core fabric 10 and the paper supporting fabric layer 11 so as to lock the three fabrics together. As explained hereinabove, it may be preferred to perform the needling operation at inclined angles to the plane of the laminate, such as by disposing the needling device to drive needles through the laminate in angular directions as shown at 16 and 17 in FIG. 8. Obviously, either of the needling devices 16 or 17 could be eliminated if desired.

FIG. 3 of the drawing herewith illustrates how the core fabric 10 is disposed in the structure so that the warp threads thereof run lengthwise of the felt belt to be constructed, whereby the warp yarns of the core fabric are disposed to function most efliciently in carrying the belt tension loads. On the other hand, the bias-disposed fabrics 11-12 function to diagonally brace the finished belt as explained hereinabove whereby the felt will not tend to skew in service in response to nip loads thereon; although the finished felt assembly may be relatively lightweight with resultant improved drainage and production characteristics. It can at the same time minimize the paper product surface unevenness because the yarns of the fabric in contact with the paper product at no time leave this surface in order to weave in with the load-carrying warp yarns, which are always taut in operation, and which would cause a pocket or void in the surface aforementioned by keeping the filling yarn withdrawn from it.

As shown in FIG. 3, the balanced bias-disposed arrangement of the fabric 12 at the roll support side of the felt disposes the ridges which form where the fabric yarns cross each other so as to contact the support rolls and stationary and revolving cleaning devices of the system with obliquely glancing impacts, as distinguished from head-on impacts. This contributes substantially to the service life of the felt. Also, as shown in FIG. 1, the use of bias-disposed fabrics at 11-12 enables the splice zones thereof as indicated at 18-22 to be diagonally disposed and spaced apart from the cross-wise disposed splice zone 20 of the core fabric. This also smooths out the belt ride.

Thus it will be appreciated that by virtue of the combination of the features referred to hereinabove the felt of the present invention is of improved efliciency and wear-resistance. The balanced, diamond-like appearance of the surface fabrics builds into the belt a self-aligning feature which serves to keep the felt properly aligned with the rolls over which it rides. Substantial improvement in the drainage characteristics is made possible by the construction of the invention, while still providing sufiicient stability; resulting in minimization of the clogging of the felt under service conditions, and facilitates cleaning thereof; thus maintaining proper felt porosity for longer periods of time.

It will of course be appreciated that although the drawing herewith illustrates the fabric components of the felt construction of the present invention to comprise simple one-over and one-under cross weave patterns, that other fabric weaves may be employed in lieu thereof, and that the weights of yarns and sizes of the squares and diamonds of the weaves of each fabric may be varied independently to suit different preferences and specifications for use. It is also understood that the arrangement of the layers comprising the total fabric may be in any combination of diamonds and squares or boxes or rectangles. Also, the fabric components of the construction may be made from a large variety of fiber yarns, both natural and synthetic and/or mixtures thereof; and from synthetic filaments. Obviously the essential advantages of the invention will be obtained when using only two fabrics or four or more fabrics, as may be dictated by different operational requirements. The angle of inclination of the needling operation to the plane of the laminate may, of course, be varied to suit different conditions as explained herein-above, to provide maximum fiber interlock performance and fabric stability.

By Way of another example, as shown in FIG. 4, a felt of the invention may be constructed to comprise a base of core fabric 10 carrying a bias-disposed fabric 24 upon which is placed a fiber batt 25; the laminate being needled together as indicated at 26 so that the components are integrated into the form of a reinforced felt as explained hereinabove. As previously stated, the needling process may be performed normal to or inclined to the plane of the laminate so as to internally t-ie together the components with fibers projecting from one surface of the finished felt as indicated at 28. If preferred, the entire felt (or any fabric component thereof) may be fulled as an incident to the manufacture of the felt, in accord with conventional practice to achieve desired physical characteristics of the finished product. Thus, it will be appreciated that a felt of the present invention will be of improved stability characteristics in combination with improved weight and drainage and service life characteristics. The nature of the felt construction renders it invulnerable to ravelling either as a result of wearing or rubbing edgewise against stationary structures While running on the papermaking machine.

The further improved water drainage capability of the finished felt of the present invention is obtained by causing the direction of the needle travel to be inclined back- Wardly relative to the plane of the laminate. Thus the fibers are driven angularly through the laminate and at the same time backwardly inclined water drainage channels are thereby formed through the laminate in such manner as to be residual therein throughout the body of the finished felt; it being particularly noted that the drainage channels so formed are disposed so as to incline downwardly and rearwardly through the felt body in relation to the direction of travel of the felt and of its entry into the nip between the squeeze rollers of the papermaking machine.

By way of example, one specific form of papermakers felt of the invention is illustrated'herein to comprise a plurality of fabric layers designated 10, 12 (\FIG. 6) and abatt 14 needled together to provide an integral felt. The fabric piece 10 is shown disposed below a single balanced bias-disposed fabric 12 and the batt 14, and thus the obliquely disposed fabric 12 mechanically reinforces the core fabric 10 against skewing as the felt traverses the papermaker felt support roller system, and otherwise stabilizes the felt in such manner that this belt may be constructed so as to be extremely light-weight and yet will be stable in operation. The assemblage is needled together by means of any suitable gang needling device, such as illustrated at 15 (FIG. 6).

As shown in FIG. 6, the needling operation operates to drive fibers from the batt 14 and fabric layer 12 through the core fabric 10 so as to lock the three components together. As explained hereinabove, the needling operation is performed at inclined angles to the plane of the laminate so as to provide water drainage channels as indicated at 16 (FIG. 7) through the integrated'felt structure which is shown in FIG. 7 at 18.

FIG. 7 of the drawing herewith illustrates how the Water channels 16 are disposed in the structure so as to facilitate water drainage from the nip zone of the paper machine press rolls, examples of which are indicated at 20, 22, and into the water draw olf ports 23 of thesuction press roll 22 when used. This contributes substantially to the effi ciency of operation of the suction press roll 22 while at the same time smoothly supporting the paper pulp which is illustrated at 24. Studies of the action of press rollers on felts have revealed that when a water-laden felt enters the nip zone and is compressed between the rollers the water therein is driven backward through the felt structure until it finds escape through the bottom surface of the felt. Thus, it will be evident that by virtue of the present invention and provision of water channels back-slanted through the felt body, expression of the water load from the felt is greatly facilitated. It appears that the water occupying the drainage channels is under heavy pressures,

' and thereby tends to maintain the drainage channels in open condition despite the pressures applied by the rollers at opposite surfaces of the felt. Thus the present invention results in minimization of the clogging of the felt under service conditions, .and facilitates self-cleaning thereof; thus maintaining improved felt porosity for longer periods of time.

it will of course be appreciated that although the drawing herewith illustrates the fabric components of the felt construction of the present invention to comprise simple one-over and one-under cross Weave patterns, other fabric weaves may be employed in lieu thereof, and that the weights of yarns and sizes of the squares and patterns of the weaves of each fabric may be varied independently to suit different preferences and specifications for use. Also, the fabric components of the construction, may be made from a large variety of fiber yarns, both natural and synthetic and/ or mixtures thereof; and from synthetic filaments. Obviously, the essential advantages of the invention will be obtained when using only two components, comprising a base fabric with one or more fabrics or with one or more batts, as may be dictated by different operational requirements. The precise angle of inclination of the needling operation to the plane of the laminate may, of course, be varied to suit different conditions as explained hereinabove, to provide maximum drainage capability and fiber interlock and fabric stability results.

Although only a few specific forms of the invention have been illustrated and described in detail hereinabove, it will be understood that various changes may be made therein without departing from the spirit of the invention or the scope of the following claims.

We claim:

1. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising a fabric consisting of cross- Woven strands disposed bias-wise to the direction of belt travel, and a stabilizing fabrication needled into integrated relation with said fabric to skew-brace the latter and to provide at one face thereof a surface comprising fibre ends projecting angularly from the plane thereof.

2. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermakin-g material, said felt comprising separate superposed fabrics each consisting of cross-woven fibre strands, one of said fabrics being disposed bias-wise to the direction of belt travel, said fabrics being integrated by a needling process whereby fibres from said fabrics are driven transversely throughout the felt to interlock said fabrics, said transversely disposed fibres projecting from one surface of said felt to provide thereat a paper material supporting nap cushion.

3. A papermakers felt for use in a belt on papermaki-ng machinery for supporting and draining papermaking material, said "felt including a fabric consisting of crosswoven' strands disposed bias-wise to the direction of belt travel and a stabilizing fabrication of fibre batt form needled into integrated relation with said fabric to skewbrace the latter.

4. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising three separate superposed fabrics each consisting of cross-woven strands, the outer two of said fabrics being disposed bias-wise to the direction of belt travel while the inner fabric is square-wise thereto, said fabrics being integrated by a needling process whereby fibres from said fabrics are driven transversely throughout the felt to interlock said fabrics, said transversely disposed fibres projecting from one surface of said felt to provide thereat a paper material supporting nap cushion.

5. A papermakers felt for use in a belt on papermakin-g machinery for supporting and draining 'papermaking material, said felt comprising superposed fabrics consisting of cross-woven strands, one of said fabrics being disposed bias-wise to the direction of belt travel, and a stabilizing fabrication needled into integrated relation with 7 said fabrics to skew-brace the latter and to provide at one face of the felt a surface comprising fibre ends projecting angularly from the plane thereof.

6. A papermakers felt for use in a belt on papermaking machinery for supporting and draining paperrnaking material, said felt comprising separate fabrics each consisting of cross-woven strands, one of said fabrics being disposed bias-wise to the direction of belt travel while another of said fabrics is disposed square-wise thereto, said fabrics being integrated by a needling process whereby fibres from said fabrics are driven transversely throughout the felt to interlock said fabrics.

7. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising a fabric consisting of crosswoven strands disposed bias-wise to the direction of belt travel, and a stabilizing fabrication needled angularly into integrated relation with said fabric to skew-brace the latter and to provide at one face thereof a surface comprising fibre ends projecting angularly from the plane thereof.

8. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising separate fabrics each consisting of cross-Woven strands, one of said fabrics being disposed bias-wise to the direction of belt travel While another of said fabrics is disposed square-wise thereto, said fabrics being integrated by a needling process Whereby fibres from said fabrics are driven angularly throughout the felt in intersecting directions to interlock said fabrics.

9. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising a fabric consisting of crosswoven strands disposed bias-wise to the direction of belt travel and a stabilizing fabrication needled into integrated relation with said fabric to skew-brace the latter and to provide at one face thereof a surface comprising fibre ends projecting angularly from the plane thereof, said needling being angled rearwardly relative to the direction of travel of the felt belt when in use to provide drainage channels so inclined.

10. A paperrnakers felt for .use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising separate superposed fabrics each consisting of cross-woven fibre strands, one of said fabrics being disposed bias-wide to the direction of belt travel, said fabrics being integrated by a needling process whereby fibres from said fabrics are driven transversely throughout the felt to interlock said fabrics, said transversely disposed fibres projecting from one surface of said felt to provide thereat a paper material supporting nap cushion, said needling being angled rearwardly relative to the direction of travel of the felt belt when in use to provide drainage channels so inclined.

11. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt including a fabric consisting of crosswoven strands disposed bias-wise to the direction of belt travel and a stabilizing fabrication of fibre batt form needled into integrated relation with said fabric to skewbrace the latter, said needling being angled rearwardly relative to the direction of travel of the felt belt when in use to provide drainage channels so inclined.

12. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising three separate superposed fabrics each consisting of cross-Woven strands, the outer two of said fabrics being disposed bias-wise to the direction of belt travel while the inner fabric is square- Wise thereto, said fabrics being integrated by a needling process whereby fibres from said fabrics are driven transversely throughout the felt to interlock said fabrics, said transversely disposed fibres projecting from one surface of said felt to provide thereat a paper material supporting nap cushion, said needling being angled rearwardly relative to the direction of travel of the felt belt when in use to provide drainage channels so inclined.

13. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising superposed fabrics consisting of cross-woven strands, one of said fabrics being disposed bias-Wise to the direction of belt travel, and a stabilizing fabrication needled into integrated relation with said fabrics -to skew-brace the latter and to provide at one face of the felt a surface comprising fibre ends projecting angularly from the plane thereof, said needling being angled rearwardly relative to the direction of travel of the felt belt when in use to provide drainage channels so inclined.

14. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising separate fabrics each consisting of cross-Woven strands, one of said fabrics being disposed bias-wise to the direction of belt travel while another of said fabrics is disposed square-wise thereto, said fabrics being integrated by a needling process whereby fibres from said fabrics are driven transversely throughout the felt to interlock said fabrics, said needling being angled rearwardly relative to the direction of travel of the felt belt when in use to provide drainage channels so inclined.

15. A papermakers felt for use in a belt on papermaking machinery for supporting and draining papermaking material, said felt comprising a fabric consisting of cross- Woven strands disposed bias-wise to the direction of belt travel, and a stabilizing fabrication needled angularly into integrated relation with said fabric to skew-brace the latter and to provide at one face thereof a surface comprising fibre ends projecting angularly from the plane thereof, said needling being angled rearwardly relative to the direction of travel of the felt belt when in use to provide drainage channels so inclined.

References Cited in the file of this patent UNITED STATES PATENTS 579,312 Arnold Mar. 23, 1897 2,165,772 Walsh et al July 11, 1939 2,581,790 Gates Jan. 8, 1952 FOREIGN PATENTS 28,578 Australia Dec. 22, 1930 

1. A PAPERMAKER''S FELT FOR USE IN A BELT ON PAPERMAKING MACHINERY FOR SUPPORTING AND DRAINING PAPERMAKING MATERIAL, SAID FELT COMPRISING A FABRIC CONSISTING OF CROSSWOVEN STRANDS DISPOSED BIAS-WISE TO THE DIRECTION OF BELT TRAVEL, AND A STABILIZING FABRICATION NEEDLED INTO INTEGRATED RELATION WITH SAID FABRIC TO SKEW-BRACE THE LATTER AND TO PROVIDE AT ONE FACE THEREOF A SURFACE COMPRISING FIBRE ENDS PROJECTING ANGULARLY FROM THE PLANE THEREOF. 